NHD-5.0-800480TF-ATXL#-CTP why don't typical timing values work?

I have a Beagle Bone Black, and looking to use the NHD-5.0-800480-ATXL with Android(Linux) source code that I found on the Internet.  When I use the timings from the internet:
   /* NewHaven - NHD-5.0-800480TF-ATXL-CTP */
        [13] = {
                .name = "NHO-5.0-800480TF",
                .width = 800,
                .height = 480,
                .hfp = 39,
                .hbp = 39,
                .hsw = 48,
                .vfp = 32,
                .vbp = 32,
                .vsw = 3,
                .pxl_clk = 45000000,
                .invert_pxl_clk = 1,
        },

The display looks ok, but not great (a white line at the top)

and then run using the Typical values in the datasheet, which I thought would provide a better fit for the display:
   /* Newhaven NHD-7.0-800480TF-ATXL#-CTP */
   [11] = {
      .name = "NHD-5.0-800480TF",
      .width = 800,
      .height = 480,
      .hfp = 40,
      .hbp = 88,
      .hsw = 48,
      .vfp = 13,
      .vbp = 32,
      .vsw = 3,
      .pxl_clk = 40000000,
      .invert_pxl_clk = 1,
   },

We get an awful picture, it's readable, but shifted quite a few pixels to the right, and the gradients are hard wide lines.

Why doesn't the data sheet typical values look so bad.  How does one go about on getting the right values, I'm guessing the datasheet to the actual display driver IC would hopefully give better information?

So my question is, where am I supposed to get timing values for the best looking display, without testing the almost infinite parameters possible in the min/max data sheet recommendations?

I saw a few questions on the forum where someone posts what processor/board they are using with which display, and asks for timing.  Is this the best way, if so, I have a Beagle Bone Black and the NHD-5.0-800480-ATXL-CTP, what values should I use for:   .width = 800, .height = 480, .hfp = ?,  .hbp = ?, .hsw = ?,  .vfp = ?, .vbp = ?, .vsw = ?, .pxl_clk = ?, .invert_pxl_clk = ?

Thanks,
Jim